In digital communication receiver design, improvements in performance may require extensive system modifications that may be very costly and, in some cases, may even be impractical. Determining the right approach to achieve design improvements may depend on the optimization of a receiver system to a particular modulation type and/or to the various kinds of noises that may be introduced by a transmission channel.
Noise, such as interference from neighboring cells and multipath fading, are limiting factors for wireless system performance. A historical approach to improve the performance of receivers that may require extensive system modifications is to reduce the effect of interference by using multiple antennas, often referred to as receive or antenna diversity. However, receiving signals from multiple antennas increases hardware and/or software complexity resulting in higher implementation costs. In contrast to multiple antenna approach,—the use of single antennas may, in some instances, achieve substantial co-channel interference cancellation for GSM/GPRS/EDGE system with moderate cost.
Other approach to achieve design improvements is to explore signal interdependency or redundancy of communication systems. For example, the optimization of a receiver system may be based on whether the signals being received, generally in the form of successive symbols or information bits, are interdependent. Signals received from, for example, a convolutional encoder, transmit with partial response, multipath channel, etc., may be interdependent signals, that is, signals with memory. Equalization and decoding techniques may be necessary to achieve system improvement.
Improvements in the design and implementation of optimized receivers may require modifications to the application of conventional techniques such as MLSE algorithm, the Viterbi algorithm, the MAP algorithm, and/or the application of new techniques that address interference from neighboring cells and multipath fading and the nature of the signals transmitted. Moreover, optimized receivers may also need to implement techniques that enable the reduction of signal interference without extensive and costly increases in hardware and/or software complexity.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.